This invention relates to air-assist fuel injection systems and more particularly to such injection systems having oxygen enrichment.
Air-assist fuel injectors have been proposed to improve the operating efficiency and emissions of internal combustion engines. These devices mix air with a fuel charge that is then injected directly into the engine combustion cylinder. The air-assist improves the atomization and distribution of the fuel charge as it enters the air within the combustion chamber of the cylinder. Air is separately ingested in a normal manner into the engine combustion chamber and may be compressed prior to the air-assisted fuel injection.
Many air-assisted fuel injectors are known in the prior art. U.S. Pat. No. 5,353,991 issued Oct. 11, 1994 assigned to General Motors Corp. and U.S. Pat. No. 5,730,369 issued Mar. 24, 1998 assigned to General Motors Corp. are examples of air-assisted fuel injectors that might employ the present invention.
It is an object of this invention to provide an improved air-assist fuel injection system having oxygen enrichment.
In one aspect of the present invention, a compressed air stream with oxygen enrichment is supplied to a fuel injector. In another aspect of the present invention, an oxygen-permeable membrane filter is disposed upstream of the compressor that is supplying air to the injector. In yet another aspect of the present invention, an air-assist fuel injection system incorporates a membrane filter that permits a freer passage of oxygen compared to that of nitrogen.
In still another aspect of the present invention, an oxygen-enriched, air-assist fuel injection system produced improved ignitability and flame propagation rate of air/fuel mixtures in an internal combustion engine. In a further aspect of the present invention, an oxygen-enriched, air-assist fuel injection system provides improved efficiency and reduced unburned fuel emissions in an internal combustion engine. In a yet further aspect of the present invention, a leaner air/fuel ratio is available with the oxygen-enriched, air-assist fuel injection system.
An oxygen enrichment device is positioned in an air-assist fuel injection system downstream of the air filter and upstream of the throttle body in branch passage. The oxygen enrichment device permits the passage of oxygen more freely than the passage of nitrogen. The output of the oxygen enrichment device is in fluid communication with a compressor that supplies a charge of air to the fuel injector. A bypass valve controls the amount of oxygen-enriched gas flow that is supplied to the injectors. Oxygen enrichment devices are available from Compact Membrane Systems, Inc. One such device is sold under the product designation 7-2AG.